Existing locks are mounted in a door by a lock case/lock housing of a lock being bolted in the door leaf by two wood-screws through a selvage connected with the lock case. By such an arrangement, the lock case is anchored in the door leaf only by these screws, the breaking security being relatively low for such locks. Accordingly, existing lock mountings constitute a weakening in the door leaf by the same having been provided with a recess for the lock case.